It is well known that ethylene oxide (C.sub.2 H.sub.4 O) can be used in pure form for the sterilization of heat-sensitive plastics. Preferably, however, it is used in admixture with one or more inert gases, such as carbon dioxide or various chlorofluorocarbons, such as freon 11 (CFCl.sub.3) or freon 12 (CCl.sub.2 F.sub.2). In a number of these mixtures which are now being marketed the inert gas serves only as a complement so as to render the mixture non-flammable, and thus also non-explosive in air.
An example of a customary sterilizing gas mixture of this type is one including about 12% by weight ethylene oxide and about 88% by weight freon 12. The reason for using such a composition is that ethylene oxide is non-flammable in air in admixture with freon 12, if the admixture contains below approximately 14 to 15% by weight of the ethylene oxide. Since ethylene oxide and freon 12 have approximately equal costs of manufacture, it would be desirable from an economic point of view to recover both of these components, or at least the major component, i.e. the freon.
It is known, as shown for example in U.S. Pat. No. 4,249,917, that these two components can be recovered simultaneously by dissolving them both in a common solvent. However, in view of the need for simultaneous dissolution of both such components in this system, great demands are placed upon the solvent to be so utilized.
In accordance with U.S. Pat. No. 4,112,054 the ethylene oxide is removed from a gaseous mixture by a process which includes its conversion to ethylene glycol and polyethylene glycol. In the case of this process, however, it is also only very special solvents which can be used.
It is also known, as shown for example in U.S. Pat. No. 3,372,980, that the gaseous mixture may be re-used as such, but only in connection with very accurate control of its composition. In normal sterilization processes, however, the gaseous mixture will sooner or later become diluted with an amount of air such that it will no longer be safe to utilize. In such situations it then becomes necessary to either substitute a new gaseous mixture, or regenerate the gaseous mixture in some way.
Finally, it is also well known that ethylene oxide is soluble in water as mentioned, for example, in U.S. Pat. No. 4,221,727; British Pat. No. 564,646 and U.S. Pat. No. 3,964,980.